An Australian air force pilot steers his AP-3C Orion over the southern Indian Ocean during the search for MH370. Photograph: Xinhua Press/Corbis

Military aircraft and ships were due to resume their hunt for possible debris from the missing Malaysia Airlines flight MH370 at dawn, but experts warned strong currents and poor weather conditions in the southern Indian Ocean were likely to make the search a long and arduous process.

Australian and US aircraft dispatched to the area could not find the objects, which were detected in images captured four days ago, and search operations ended as night fell on the region.

Malaysia’s transport minister described the pictures, which showed objects estimated to be between five to 24 metres (16ft to 79ft) long, as a credible lead in the 12-day search for flight MH370. But nothing has so far been found.

The captain of the first Australian air force AP-3C Orion plane to return from the search area described the weather conditions as extremely bad, with rough seas and high winds, and with poor visibility. A US Poseidon P-8 aircraft also drew a blank.

The Hoegh St Petersburg, a Norwegian car carrier that was the first ship to arrive in an area 2,500km (1,500 miles) south-west of Perth where two objects cited as potential parts of MH370 were sighted, continued searching through the hours of darkness.

“We will continue searching during the night at reduced speed and with all spotlights available, and we will increase the speed again when the light comes back,” Ingar Skiaker, chief executive of Hoegh Autoliners, told a news conference in Oslo.

“We don’t know what that satellite saw until we can get a much better, much closer look at it but this is the first tangible breakthrough in what up till now has been an utterly baffling mystery,” Abbott said.

But the Australian defence minister, David Johnston, appeared more circumspect. “Expectations will obviously be built. I want to say that let’s just be patient and try and find out what this satellite reference is,” Johnston told the Australian Broadcasting Corporation.

“[The southern Indian Ocean] is an extraordinarily remote part of the world … This is a very difficult logistical problem. We’re several days away, I think, from really having an idea of the credibility and veracity of this report.”

Asked if he thought this was the best lead in the search so far, Johnston said: “Well, there’s been several ‘best leads’ along the way. It’s almost a fortnight since this aircraft went off the radar. I think this is a potentially credible sighting that must be investigated but let’s just not get our hopes up. There’s a lot of debris in the water out there. It’s a very long way away.”

Professor Alexander Babanin, director of the Centre for Ocean Engineering, Science and Technology at Swinburne University of Technology in Australia, said that the search was taking place in an area of deep ocean and strong currents, where waves can reach up to six metres in stormy weather.

He noted that floating debris could have been carried 100km away from their position in the satellite photographs, an estimate based on looking at average conditions.

Fragments could be spread over 50km or so, and material suspended beneath the surface could be carried perhaps even further, because ocean currents can be stronger than wave-induced currents, he said.

The search for the Boeing 777 has drawn in assets and expertise from 26 countries. The Royal Australian Navy ship HMAS Success is expected to arrive in the search area within a few days and the Ministry of Defence confirmed that the UK was sending HMS Echo, a coastal survey ship.

On Wednesday, US president Barack Obama said finding out what happened to the Beijing-bound flight was a top priority for the United States, adding: “It’s a big piece of planet that we’re searching and sometimes these things take time, but we hope and pray that we can get to the bottom of what happened.”

MH370 vanished shortly after taking off from Kuala Lumpur early on 8 March with 239 people on board. Officials have said they believe it was deliberately diverted from its route to Beijing, but have not ruled out a catastrophic event.

Hishammuddin Hussein, Malaysia’s transport minister, said of the possible debris: “Any leads that we receive must be corroborated and verified, because if found false not only will it jeopardise our search but it will give false hope to the families.”

He said the search was continuing in both the northern and southern search arcs delineated by analysis of satellite data, which sweep north to Kazakhstan and down to the southern Indian Ocean, across 2.24m square nautical miles of land and sea.

Malaysian officials held a meeting Thursday night with the relatives in a hotel near Kuala Lumpur, but journalists were kept away. After the meeting, groups of people left looking distraught, the Associated Press reported. Hamid Amran, who had a child on Flight 370, said questions asked at the meeting made it “apparent that Malaysia’s military is incapable of protecting its own airspace”.

He said he “believes that my child and all the other passengers are still alive. I will not give up hope.”

A man who would only give his surname, Lau, said he was there to support a Chinese couple who had lost their only son. “It appears some families are slowing accepting the worst outcome,” he told the AP.

A group of Malaysian government and airline officials also flew to Beijing on Thursday night to meet families there.